JP2681390B2 - Method of joining aluminum or aluminum alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to a method for joining aluminum or aluminum alloy.

BACKGROUND OF THE INVENTION

When brazing a member made of aluminum or an aluminum alloy (hereinafter simply referred to as an aluminum alloy), if the aluminum alloy member has a simple shape and there are few joints, an Al-Si alloy of 1 to 2 mmφ is used. Torch brazing is used in which the brazing wire and flux are used to heat to about 600 ° C. However, since the melting point of aluminum alloy is as low as about 660 ° C., there is a fatal drawback that the joining member is melted by overheating. Therefore, it is desired to use a brazing material that can be used even at a low brazing temperature, and it has been proposed to use a Zn-based alloy such as Zn-Al. However, the workability of Zn-Al alloys is extremely poor,
It is extremely difficult to make a wire rod with a diameter of 1-2 mm for use in brazing a torch. Further, it is troublesome to apply the flux after supplying the brazing wire, and the workability is low.

DISCLOSURE OF THE INVENTION

A first object of the present invention is to provide a method for joining aluminum alloys which solves the melting problem of the aluminum alloys to be joined. A second object of the present invention is to provide a method for easily joining an aluminum alloy using, for example, a Zn-Al alloy, which is extremely difficult to process into a wire rod. The object of the present invention is a melting point of 340 ~ 550 ℃ aluminum or aluminum alloy brazing metal powder, the molecular weight is
Acrylic resin of 100-100,000 and molecular weight of 100-10,000
Characterized in that a composition containing an organic resin that volatilizes at a brazing temperature selected from the group of ethylene-based hydrocarbons is intervened in a joint portion of aluminum or an aluminum alloy and also a flux, and then heated. It is achieved by the joining method of aluminum or aluminum alloy. Further, a composition containing a metal powder for brazing aluminum or aluminum alloy having a melting point of 340 to 550 ° C., an organic resin that volatilizes at the brazing temperature, and a flux is interposed in a joint portion of aluminum or an aluminum alloy and then heated. And an aluminum or aluminum alloy joining method. Here, as the brazing metal powder having a melting point of about 340 to 550 ° C., there is Zn or a Zn—Al based alloy containing Zn as a main component. If the melting point of the metal powder used as the brazing material is lower than 340 ° C, a problem may occur in the bonding strength, and if the melting point exceeds 550 ° C, the base material of the aluminum alloy may become The melting point of brazing metal powder is about
It is necessary to be 340-550 degreeC. Organic resin (binder) that volatilizes at brazing temperature
The term, when heated to a brazing temperature, does not mean that a large amount of carbon residue is generated by carbonization of the organic resin, but for example, a resin in which carbon chains are broken and volatilized, and disappears, Such a resin has a molecular weight of about 1000-
There are 100,000 acrylic resins. In addition to such acrylic resin, a resin such as ethylene hydrocarbon having a molecular weight of about 100 to 10,000 can be appropriately selected and used. The brazing metal powder and the binder may be mixed in such a ratio that the viscosity of the mixed dispersion becomes about 10 to 5000 cps. That is, the blending ratio of these components should be such that the brazing composition does not immediately drip during application. However, the fact that the relative amount of the binder is large means that the brazing metal powder is small, and if the brazing metal powder is too small, the brazing will not work well, so the brazing metal powder / binder is about 2 or more. Is desirable. Then, these brazing metal powder and organic resin that volatilizes at the brazing temperature, and if necessary, a flux having a melting point near the melting point of the brazing material may be mixed and dispersed in water or an organic solvent. The dispersion liquid may be attached to a portion to be brazed, and predetermined brazing may be performed. If the flux components are mixed and dispersed in the above-mentioned mixed dispersion liquid, the subsequent flux coating step can be reduced, and the amount necessary for brazing can be added, which is advantageous in terms of cost. And as a flux, a fluoride-based one such as CsF-AlF ₃ , ZnCl ₂ -NaF-NH ₄ Cl, KCl-LiCl-NaF, C
There are chloride-based compounds such as aCl ₂ -KCl-ZnCl ₂ , and other various fluxes may be used. As a method for supplying a composition containing a brazing metal powder or an organic resin that volatilizes at a brazing temperature to the joint, extrusion from a tube, supply by a pump, roller coating method, brush coating method, spray method, etc. are considered. However, any means may be adopted.

Example 1 Al-70 wt% Zn alloy powder having an average particle size of about 70 μm and a melting point of 500 ° C. and a 5% acrylic resin (molecular weight 1000 to 100000) aqueous solution were mixed and dispersed at a ratio of 2: 1 (weight ratio). Thus, a brazing composition was obtained. This brazing composition was manufactured by extruding an A3003 alloy into an extruded tube 1 and an A3003 alloy into an extruded rod 2
With a metering pump at the joint of the assembly as shown in Fig. 1
1 g was supplied and adhered, then a chloride-based flux aqueous solution was applied, and torch brazing was performed.

Example 2 Instead of the composition for mixing and dispersing brazing of Al-70 wt% Zn alloy powder having a melting point of 500 ° C. and 5% acrylic resin aqueous solution in Example 1, Al-70 wt% having a melting point of 500 ° C. Brazing was carried out in the same manner as in Example 1 using a composition for brazing and dispersing a Zn alloy powder, a 5% acrylic resin aqueous solution, and a fluoride flux (60: 30: 1 by weight ratio). However, the application of the chloride flux, which was performed after supplying the brazing composition to the joint, was omitted.

Comparative Example 1 Instead of the brazing composition in Example 1, melting point
Torch brazing was performed using an Al-12 wt% Si alloy brazing wire at 580 ° C and applying a chloride flux.

【Characteristic】

In each of the above examples, brazeability, melting condition of joint and CA
The pitting corrosion resistance after 720 hours of SS test was examined, and the results are shown in Table 1. From this, according to the present invention, melting of the aluminum alloy does not pose a problem, and the brazing property is good, and
It can be seen that there is no problem in joining and the pitting corrosion resistance is also excellent. Further, since it is not necessary to process the wire rod, it can be implemented at low cost.

[Brief description of the drawings]

 FIG. 1 is an assembly drawing of an extruded tube and a rod. 1 ... Extruded tube, 2 ... Rod 2.

Claims (2)

(57) [Claims] 1. A metal powder for brazing aluminum or aluminum alloy having a melting point of 340 to 550 ° C., having a molecular weight of 1000 to 1000.
A composition containing an acrylic resin of 00 and an organic resin that volatilizes at a brazing temperature selected from the group of ethylene hydrocarbons having a molecular weight of 100 to 10,000 is intervened in the joint part of aluminum or aluminum alloy, and flux is also present. A method of joining aluminum or aluminum alloy, characterized by interposing and then heating. 2. A composition containing a metal powder for brazing aluminum or aluminum alloy having a melting point of 340 to 550 ° C., an organic resin which volatilizes at a brazing temperature, and a flux,
A method for joining aluminum or an aluminum alloy, which comprises interposing the aluminum or aluminum alloy at a joint and then heating.